This script is real good for noting whether a kanji reading being requested is kunyomi or onyomi.
My only caution is that the indication of kunyomi/onyomi can itself be a “cue” in the review process that might help you identify the kanji when you otherwise couldn’t, since only a moderately small selection of kanji are taught without their on’yomi. For example, it’s really easy to know you’re being asked for 暑 and not 着 because it says “kun’yomi”, but they visually look fairly similar and I’ve confused them at least once.